Crystalline Dragon

Huge dragon, any chaotic

Armor Class

20 (natural armor)

Hit Points

270 (20d12+140)

Speed

40 ft., fly 80 ft.

Saves

Dex +8, Con +13, Wis +9, Cha +14

Skills

Insight +9, Perception +15, Intimidation +14

Damage Immunities

bludgeoning, piercing, and slashing from nonmagical weapons that aren't adamantine

Senses

blindsight 60 ft., darkvision 120 ft.

Languages

Common, Draconic

Challenge

18

Legendary Resistance (3/Day)

If the dragon fails a saving throw, it can choose to succeed instead.

Prismatic Immunity

The dragon can use its bonus action to gain immunity to one of the following damage types: acid, cold, fire, or lightning. The immunity lasts until the dragon uses this ability again.

Actions

Multiattack

The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite

Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 20 (2d10+9) piercing damage.

Claw

Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 13 (2d6+9) slashing damage.

Tail

Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit:15 (2d8+9) bludgeoning damage.

Frightful Presence

Each creature of the dragon's choice that is within 20 feet of the dragon and aware of it must succeed on a DC 22 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.

Prismatic Breath (Recharge 5-6)

The dragon exhales multicolored rays of light. Each creature in a 60-foot cone must make a DC 21 Dexterity saving throw. For each target, roll a d8 to determine which color ray affects it. 1. Red. The target takes 55 (10d10) fire damage on a failed save, or half as much damage on a successful one. 1. Orange. The target takes 55 (10d10) acid damage on a failed save, or half as much damage on a successful one. 1. Yellow. The target takes 55 (10d10) lightning damage on a failed save, or half as much damage on a successful one. 1. Green. The target takes 55 (10d10) poison damage on a failed save, or half as much damage on a successful one. 1. Blue. The target takes 55 (10d10) cold damage on a failed save, or half as much damage on a successful one. 1. Indigo. On a failed save, the target is restrained. It must then make a DC 21 Constitution saving throw at the end of each of its turns. If it successfully saves three times, the effect ends. If it fails its save three times, it permanently turns to stone and is subjected to the petrified condition. 1. Violet. On a failed save, the target is blinded for 1 minute 1. Special. The target is struck by two rays. Roll twice more, rerolling any 8.

Legendary actions

Legendary Actions

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.

Detect

The dragon makes a Wisdom (Perception) check.

Tail Attack

The dragon makes a tail attack.

Wing Attack (Costs 2 Actions)

The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 23 Dexterity saving throw or take 16 (2d6+9) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.